Brake discs are known comprising a bell, an annular portion called braking band extending therefrom, which is intended to co-operate with the pads of a caliper. In ventilated discs, the braking band is made of a couple of mutually facing plates which are connected to each other by a plurality of connection elements, typically in the form of pins or tabs. The outer surfaces of the two plates define opposite braking surfaces. The inner facing surfaces define, in conjunction with the pins or tabs, ventilation ducts for cooling the disc for the air to flow therein in a centrifugal direction during the rotation movement of the disc.
In order to improve the ventilation and reduce cracks resulting from temperature changes, ventilated brake discs have been proposed having shaped connection elements in order to enhance the effectiveness of the ventilation ducts.
WO 2008/136032 A2, in the name of the Applicant, discloses ventilated brake discs comprising joining elements in the form of tabs distributed in two concentrical arrays; the tabs are elongated in substantially radial directions with a concavity facing the preferred direction of rotation of the disc.
A ventilated brake disc in WO 2008/136032 A2 provides connection elements in the form of pins distributed in three concentric arrays, where the radially outermost array comprises pins with a drop-shaped cross-section, a radially innermost array with radially elongate pins, and a radially intermediate array with pins having a rhombus cross-section, with rounded vertexes and the main diagonal orientated in substantially radial directions.
WO 2012/164465 A1 discloses a ventilated brake disc with connection elements in the form of pins distributed in three concentric arrays, where the pins of the radially intermediate radially intermediate array have a shaped cross-section such as a star with four rounded points. Between the pins of the radially outermost array, axially aligned projections are placed projecting from the two facing inner surfaces of the two plates of the braking band.